[49.03] Global Properties of the Ejecta Absorptions in the Spectrum of Eta Carinae

Between 2400A to 3160A, we have identified approximately 500
absorption line complexes, each with up to 20 velocity
components. Lines of Fe I, Fe II, Ti II, V II, Ni II, Co II,
Mn II, Mg I, Mg II and Na I have been identified.
Surprisingly, most of the lines originate from energy levels
significantly above the ground level. This is indicative of
optical pumping from the Central Source. Line widths and
population of various levels are non-thermal. The relative
column densities change with velocity. For example, Fe II
column densities for one transition arising from ~0.1eV
increase with ejecta velocity while Fe II column densities
for another transition decreases with velocity. This may be
due to softening of the ultraviolet radiation that pumps the
various ions (neutrals) with velocity. If we assume that the
distance of each system scales with distance from the
Central Source, only a thirty percent change in distance is
noted; yet the ratio of column densities for the Fe II
examples given above changes by nearly thirty-fold.

If the ejecta distance scales with distance from Eta
Carinae, then it is likely that this ejecta originated at
nearly the same time. The geometry of the Homunculus has
been determined to be a double-lobed structure tilted out of
the plane of the sky. We interpret the ejecta as being in
the wall of the Southwest lobe, and that this wall just
happens to be in line of sight from Eta Carinae to the
observer.

As Eta Carinae enters into the upcoming minimum, we are
already seeing some evidence for changes in column densities
due to changes in ultraviolet fluxes. This is reinforced by
IUE observations that we have recently re-analyzed with
respect to the 5.52 year (2020+/-10 days) spectroscopic
period.

Observations were done through STScI and funding was through
the STIS GTO resources.

The author(s) of this abstract have provided an email address
for comments about the abstract:
gull@sea.gsfc.nasa.gov